Manufacture of semiconductor devices such as liquid crystal displays, flat panel displays, and thin film transistors involves use of processing chambers in which various processes are carried out. Many of these processes can result in accumulation of material on chamber surfaces as a by-product of processes in which material is deposited on a substrate in layers (as by chemical vapor deposition (CVD), physical vapor deposition (PVD), thermal evaporation, etc.), or in which material is etched from substrate surfaces. The accumulated material can crumble from chamber surfaces and cause contamination of the sensitive devices being processed in the chamber. Accordingly, processing chambers must be cleaned of accumulated materials frequently, such as after processing of each substrate or of several substrates. To clean the chamber surfaces of a processing chamber, it is known to provide a cleaning gas such as NF3, to dissociate the cleaning gas to form a reactive gas species (e.g., fluorine ions and radicals) and to flow the gas including the reactive gas species into the processing chamber. The reactive species clean the chamber surfaces by forming volatile compounds with the material accumulated on those surfaces. The volatile reaction products and unused reactive species are exhausted from the chamber by a conventional exhaust pump.
Unfortunately, such chamber cleaning processes conventionally consume considerable quantities of cleaning gases, and also produce undesirable by-products such as hazardous air pollutants (HAPs) and perfluorocompounds (PFCs), which are greenhouse gases that may contribute to global warming. Accordingly, it would be desirable to provide improved processing chamber cleaning methods which reduce consumption of cleaning gases and emission of undesirable products.